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Subtropical Storm ALBERTO
ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM Subtropical Storm Alberto Discussion Number 3 NWS National Hurricane Center Miami FL AL012018 1000 PM CDT Fri May 25 2018 Satellite imagery, earlier aircraft data, and surface observations indicate that Alberto is rather disorganized. A prominent mid-level center is near the western tip of Cuba, with the convection somewhat organized around it. However, the low-level center is about 170 n mi south-southwest of the mid-level center. There are no recent observations of gale-force winds, so the initial intensity will remain an uncertain 35 kt. An upper-level trough just to the west and northwest of the cyclone is advecting cool and dry air into Alberto, and thus the system remains a subtropical cyclone at this time. The initial motion is a somewhat uncertain 090/4. Alberto should turn northward during the next 12 h or so in response to the nearby upper-level trough, with this motion continuing through about 36 h. After that, a north-northwestward motion is likely as the aforementioned trough becomes a closed low over the central Gulf of Mexico and Alberto moves around the northeast side. This evolution should cause Alberto to move through the eastern Gulf of Mexico during the next 2-3 days, and then make landfall on the northern Gulf Coast between 72-96 h. After landfall, Alberto should continue northward through the southeastern United States. The new forecast track is nudged a bit to the east of the previous track during the first 36 h based on the initial position, and it lies just to the west of the consensus models. One uncertainty in the track forecast is the possibility that the center could re-form to the north, which at the least could change the timing of the forecast track. The dynamical models forecast Alberto to reach an area of stronger upper-level divergence in about 24 h, with the models agreeing on more significant development starting about that time. The intensity forecast shows a slower development rate for the first 24 h than the previous forecast, then shows a faster development to the 55-kt peak intensity of the previous forecast. After landfall, Alberto should quickly weaken over land. The new intensity forecast is near the intensity consensus and the SHIPS model. Some of the intensity guidance suggests that Alberto could become a hurricane before landfall. If the guidance trends stronger, a hurricane watch could be needed for a portion of the Gulf Coast on Saturday. KEY MESSAGES: 1. Regardless of its exact track and intensity, Alberto is expected to produce heavy rainfall and flash flooding over the northeastern Yucatan Peninsula of Mexico, western Cuba, southern Florida and the Florida Keys. Rainfall and flooding potential will increase across the central U.S. Gulf Coast region and the southeastern United States later this weekend and early next week when Alberto is expected to slow down after it moves inland. 2. Tropical-storm-force winds and hazardous storm surge are possible along portions of the central and eastern U.S. Gulf Coast beginning on Sunday, including areas well east of the track of Alberto's center, and tropical storm and storm surge watches are in effect for portions of these areas. Residents in the watch areas are encouraged not to focus on the details of the forecast track of Alberto and should follow any guidance given by their local government officials. 3. Dangerous surf and rip current conditions are affecting portions of the Yucatan Peninsula and western Cuba and will likely spread along the eastern and central U.S. Gulf Coast later this weekend. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 19.4N 85.7W 35 KT 40 MPH 12H 26/1200Z 20.7N 85.4W 35 KT 40 MPH 24H 27/0000Z 22.9N 85.1W 40 KT 45 MPH 36H 27/1200Z 25.4N 85.4W 50 KT 60 MPH 48H 28/0000Z 27.0N 86.3W 55 KT 65 MPH...TROPICAL CYCLONE 72H 29/0000Z 29.5N 87.5W 55 KT 65 MPH...TROPICAL CYCLONE 96H 30/0000Z 32.5N 88.0W 30 KT 35 MPH...INLAND 120H 31/0000Z 36.5N 85.5W 20 KT 25 MPH...INLAND $$ Forecaster Beven NNNN